GB829413A - Improvements in and relating to the adsorption of organic vapours - Google Patents

Abstract

A process for recovering organic compounds from gas streams in which they are present in vapour form comprises passing the stream over granules of a polyalkene whereby the organic compounds are absorbed on the granules and thereafter desorbing the organic compounds or compound from the granules. The polyalkene, e.g. polyethylene and polypropylenes, is usually produced by a low-pressure polymerization process. The optimum size of the granules used is between BSS 25 and 72 and a bulk density of 0.12 to 0.14 gms/ml. The desorption is effected by passing an inert gas through the loaded granules and amongst organic compounds which can be efficiently collected from gases containing them by means of isotactical polypropylene are iso-octane, benzene, and carbon tetrachloride. All these can be efficiently desorbed subsequently by passing a stream of inert gas such as nitrogen through the loaded granules. Other compounds which can be efficiently adsorbed and desorbed are: aliphatic alcohols such as methanol, ethanol, iso-propanol, n - propanol, iso - butanol, n - butanol; alkanes, such as n-pentane, n-hexane, n-heptane; alkenes such as pentene-1 and hexene-1; polymer alkenes, e.g. heptenes, nonenes; aromatic hydrocarbons, e.g. toluene, o-, m- and p-xylenes; cyclo-alkanes, e.g. cyclopentane, methyl-cyclopentane, cyclo-hexane, methyl-cyclohexane; and alkyl ethers, e.g. di-isobutyl, iso-butyl/n-butyl, di-n-butyl, n-butyl/iso-amyl, and n-amyl/n-butyl, ethers.ALSO:Polyethylene and isotatic polypropylene made by a low-pressure process, and of molecular weight between 50,000 to 150,000, are used as absorbents for vapours in a gas stream. The polymers have a British Standard sieves size between 25 and 75 and a packed density of 0.12 to 0.14 gm./ml.